High-temperature Sintering Step Research Articles

Ultrafast high-temperature sintering of polymer-derived ceramic thick film sensors

Polymer-derived ceramics (PDCs) find extensive applications as sensitive materials in in-situ thin/thick film sensors (TFSs) co-fabricated with components. However, the prolonged high-temperature sintering steps of PDCs inevitably lead to severe thermal damage to their co-sintered substrates. In this study, we employed an ultrafast high-temperature sintering (UHS) method, achieving rapid sintering of preceramic polymer slurry sensitive films in just a few minutes. Through direct ink writing technology, we patterned the preceramic polymer slurry, followed by UHS to prepare high-temperature ITO/SiCN TFSs. UHS-ITO/SiCN exhibited high sensitivity of microstructure, composition, and electrical characteristics to UHS parameters. The obtained ITO/SiCN resistance grid showed high electrical conductivity (706.89 S m−1 at room temperature), highly dense surface structure and excellent oxidation resistance. In an air atmosphere, the resistance drift rate of the resistance grid at 900 °C was only 0.54 %·h−1 without any protective layers. Finally, we fabricated an ITO/SiCN heat flux sensor with high sensitivity (78.75 mV/(kW·m−2)), a wide range (94.8 kW m−2), and excellent repeatability. This work has the potential to expand the application of UHS in the manufacturing of novel in-situ TFSs integrated with components.

Facile preparation of electrodes of efficient electrolyte-supported solid oxide fuel cells using a direct assembly approach

Solid oxide fuel cells (SOFCs) are the most efficient energy conversion technology to convert the chemical energy of fuels like hydrogen, natural gas, etc. to electricity. However, one of the limiting factors in the commercial viability of SOFCs technologies is the time-consuming and high-cost multiple cell fabrication processes. Here, we report the development of a facile procedure for the preparation of an electrolyte-supported cell with a Ni-Gd0.1Ce0.9O1.95 composite anode and a La0.6Sr0.4Co0.2Fe0.8O3-δ cathode, and the fabrication procedure of the electrodes decreases from four steps of screen-printing and sintering of conventional cell preparation processes to two steps of screen-printing using a direct assembly approach without the high-temperature sintering steps. The most important observation is the simultaneous formation of the electrode/electrolyte interfaces of both the anode and cathode by in situ passing a current through the directly assembled cells at 800 ℃. The power density of the directly assembled cell reaches 0.41 W cm−2 at a voltage of 0.7 V and 800 ℃, close to 0.46 W cm−2 of the sintered cell. The directly assembled cell shows comparable operational stability to the sintered cell at 800 ℃ for 100 h. This work sheds light on the facile fabrication of electrolyte-supported cells with substantially simplified preparation procedures and reduced costs.

Fabrication of Si3N4 ceramics with high thermal conductivity and flexural strength via novel two-step gas-pressure sintering

Si3N4 ceramic substrates serving as heat dissipater and supporting component are required to have excellent thermal and mechanical properties. To prepare Si3N4 with desirable properties, a novel two-step gas-pressure sintering route including a pre-sintering step followed by a high-temperature sintering step was devised. The effects of pre-sintering temperature (1500 – 1600 °C) on the phase transformation, microstructure, thermal and mechanical properties of the samples were studied. The pre-sintering temperature played an important role in adjusting the Si3N4 particles’ rearrangement and α→β transformation rate. Furthermore, the densification process for the Si3N4 ceramics prepared via the two-step gas-pressure sintering was revealed. After sintered at 1525 °C for 3 h followed by a high-temperature sintering at 1850 °C for another 3 h, the prepared Si3N4 compact with a bimodal microstructure presented the highest thermal conductivity and flexural strength of 79.42 W·m−1·K−1 and 801 MPa, respectively, which holds great application prospects as ceramic substrates.

Garnet-Based Composite Cathodes for All Solid-State Li Batteries

All-solid-state Li batteries are regarded as a highly promising system for future electrochemical energy storage. Oxide-ceramic based all-solid-state lithium batteries (ASB) can provide high intrinsic safety, extended operational temperature range and high energy density.As the first two are intrinsic to the materials system, one prerequisite to obtain high energy densities with such ASBs is the manufacturing of thick (approx. 150 µm), dual-conducting free-standing composite cathodes, analogous to that of conventional liquid electrolyte-based lithium batteries. However, the preparation of composite cathodes using oxide-ceramic electrolytes is challenging since high temperature sintering steps are necessary during electrode and cell manufacturing to achieve proper mechanical stability, contact between the individual phases and good ionic and electronic conductivity.[1, 2] For oxide-based ceramic electrolyte materials like Li7La3Zr2O12 (LLZ) or Li1+xAlxTi2-x(PO4)3 (LATP) a sintering temperature around 1000 °C is necessary. However, cathode active materials like spinels (e. g. Li2NiMn3O8) or layered materials (e. g. Li[Ni1-x-yCoxMny]O2 (NCM)) show thermal stability only to around 700 °C and the required sintering temperature for the electrolyte exceeds their thermal stability window.To mitigate these materials interactions, advanced sintering techniques like high-pressure Field Assisted Sintering Technique/ Spark Plasma Sintering (FAST/SPS) is required, as it allows low temperature consolidation.[3]Using high-pressure FAST/SPS we have developed a method to prepare thick mixed-conducting composite cathodes and half-cells at sintering temperatures as low as 700 °C. The analysis of these composite cathodes revealed well sintered pure phases and a homogenous distribution of cubic LLZ and cathode active material. Electrochemical tests showed promising electronic and ionic conductivity (0.4 mS cm-1) values and an increased capacity (4 mA cm-2) compared to cathodes with pure active material.FAST/SPS can, therefore, open new processing windows for ceramic-based ASSLBs to alleviate the problem of interphase formation.

Ambient flash sintering of reduced graphene oxide/zirconia composites: Role of reduced graphene oxide

Fabrication of graphene/ceramic composites commonly requires a high-temperature sintering step with long times as well as a vacuum or inert atmosphere, which not only results in property degradation but also significant equipment complexity and manufacturing costs. In this work, the ambient flash sintering behavior of reduced graphene oxide/3 mol% yttria-stabilized ZrO2 (rGO/3YSZ) composites utilizing rGO as both a composite component and a conductive additive is reported. When the sintering condition is carefully optimized, a dense and conductive composite can be achieved at room temperature and in the air within 20 s. The role of the rGO in the FS of the rGO/3YSZ composites is elucidated, especially with the assistance of a separate investigation on the thermal runaway behavior of the rGO. The work suggests a promising fabrication route for rGO/ceramic composites where the vacuum and furnace are not needed, which is of interest in terms of simplifying the fabrication equipment for energy and cost savings.

Fabrication and Characterization of Ice Templated Membrane Supports from Portland Cement.

Porous ceramic membranes for aqueous microfiltration and ultrafiltration processes suffer from the high-costs of material and processing. The latter is mainly due to the high-temperature sintering step. In this work, cement-based membrane supports from ultrafine Portland cement are studied as a low-cost alternative to traditional oxidic ceramic supports. An environmentally friendly freeze-casting fabrication route is applied for the fabrication of porous membrane supports. Cement membrane supports are becoming mechanically stabile after hydration reaction of cement with water, which does not require any high-temperature sintering step as in a conventional ceramic membrane fabrication process. This fabrication route, which is sintering-free, decreases the cost and environmental impact of the membrane fabrication process by eliminating extra energy consumption step during sintering. The Archimedes method, scanning electron microscopy (SEM), micro-computed tomographic (µCT), and mercury porosimetry characterize the membrane supports in respect to open porosity, pore size distribution, morphology, and connectivity. The flexural strength of the 3 mm thick membranes is in the range from 1 to 6 MPa, as obtained by the ring-on-ring tests. The obtained membrane supports possess porosity in the range between 48 and 73% depending on fabrication conditions (cooling rate and the solid content, as determined by Archimedes method enabling water flux in the range between 79 and 180 L/(h·m2) at 0.5 bar transmembrane pressure difference and 3 mm membrane thickness.

Tungsten-Doped Zinc Oxide and Indium-Zinc Oxide Films as High-Performance Electron-Transport Layers in N-I-P Perovskite Solar Cells.

Perovskite solar cells (PSCs) have attracted tremendous research attention due to their potential as a next-generation photovoltaic cell. Transition metal oxides in N–I–P structures have been widely used as electron-transporting materials but the need for a high-temperature sintering step is incompatible with flexible substrate materials and perovskite materials which cannot withstand elevated temperatures. In this work, novel metal oxides prepared by sputtering deposition were investigated as electron-transport layers in planar PSCs with the N–I–P structure. The incorporation of tungsten in the oxide layer led to a power conversion efficiency (PCE) increase from 8.23% to 16.05% due to the enhanced electron transfer and reduced back-recombination. Scanning electron microscope (SEM) images reveal that relatively large grain sizes in the perovskite phase with small grain boundaries were formed when the perovskite was deposited on tungsten-doped films. This study demonstrates that novel metal oxides can be used as in perovskite devices as electron transfer layers to improve the efficiency.

Solution-Based Synthesis of Li3PS4 Solid Electrolytes

Sulfide-based solid electrolytes have attracted much attention due to their high conductivities, which are far beyond those of oxide-based solid electrolytes.[1,2] However, They (Li2S-P2S5 system, i.e., LPS) have been normally synthesized by solid state synthesis such as mechanical ball milling. These methods require rigorous control of reaction environment as well as high temperature heat treatment and repeated pelletizing steps. In contrast, solution-based synthesis methods can induce chemical reaction among precursor particles (Li2S and P2S5) at low temperatures resulting in the formation of conductive phases of β-Li3PS4 and Li3P7S11 with only moderate thermal treatment.[3,4] The method deserves great attention since it simplifies synthesis process, yields products of great purity, and may facilitate the fabrication of composite electrodes with improved interfaces. In this work, we have developed an efficient method to form a thin solid electrolyte layer directly on Li metal using the liquid coating techniques. The formation of LPS (Li2S-P2S5) based electrolyte is achieved by rational design of the solvent and the Li, P, and S precursor ratios. The solution electrolyte can be directly coated and formed on Li metal through the in-situ formation of the solid electrolyte layer, which does not require the complex synthesis process and high temperature sintering step. Layers of thickness of < 50 mm can be fabricated and electrochemical cycling of lithium is achieved. This liquid-phase coating is a simple and straightforward technique for making a thin solid electrolyte and can be applicable to anode surface with complex contours. The new liquid coating technique holds the promise to overcome the limitations of current state solid electrolytes. [1] Kamaya, N. et al. A lithium superionic conductor. Nature Mater. 10, 682-686 (2011). [2] Yamane, H. et al. Crystal structure of a superionic conductor, Li7P3S11. Solid State Ion. 178, 1163-1167 (2007). [3] Ito, S. et al. A synthesis of crystalline Li7P3S11 solid electrolyte from 1,2-dimethoxyethane solvent. J. Power Sources 271, 342-345 (2014). [4] Liu, Z. et al. Anomalous High Ionic Conductivity of Nanoporous β-Li3PS4. J. Am. Chem. Soc. 135, 975-978 (2013).

Influences of feedstock and plasma spraying parameters on the fabrication of tubular solid oxide fuel cell anodes

This study developed a tubular solid oxide fuel cell (SOFC) anode support layer via atmospheric plasma spraying, which is considered one of the most promising methods for producing SOFCs because of its faster deposition rate and lower cost compared with other film formation processes. Plasma spraying can replace the traditional use of extrusion technology to manufacture the anode base tube, eliminating the need for high-temperature sintering steps. In this study, commercially available powders were used to make the anode of a tubular SOFC from NiO/yttria-stabilized zirconia (YSZ) powder, and Na2CO3 and polymethyl methacrylate were tested as pore-forming agents. The anode composite powder was sprayed on the graphite base pipe, and the final product was changed by altering the spraying parameters and anode powder ratio. The direct current (DC) resistance measurements showed that the conductivity of the Ni/YSZ tubular anode formed with higher power plasma spraying could reach 428.55 S/cm at 800 °C. The experimental results showed that the power and parameters of atmospheric plasma spraying could affect the porosity and electron conductivity of tubular SOFC anodes.

Effect of substrate hardness and surface roughness on the film formation of aerosol-deposited ceramic films

The aerosol deposition (AD) method is a novel ceramic coating technique that allows manufacturing of dense ceramic films at room temperature directly from ceramic powders without any high temperature sintering steps and without expensive (ultra) high vacuum processes. The deposition mechanism can be separated into two stages: the creation of an anchor layering and the subsequent film formation. Step one involves an initial plastic deformation of the substrate surface by the first impacting particles. Especially in the first stage, substrate properties affect the deposition and determine the dominant bonding mechanism. Ductile substrates can be expected to give strong film anchoring, whereas high hardness substrates might require higher particle velocities to form adhering layers. In this study, the influence of the substrate hardness in combination with the surface roughness on the deposition was investigated. Four ceramic substrates (two types of Al2O3, sapphire, and LTCC) with different hardness and surface roughness were coated with Al2O3 in order to study the formation of an anchoring layer and their effect on the deposition rate. As a result, no anchoring layer was found on the hard ceramic substrates.

High performance planar perovskite solar cells by ZnO electron transport layer engineering

ZnO as electron extraction layer in photovoltaic devices has many advantages, including high mobility and low processing temperature. However, it has been underutilized in perovskite solar cells due to the reported instabilities of perovskite layers deposited on ZnO resulting in poor device performance. Herein, we modify the ZnO layer by incorporating Cs or Li dopants in its bulk and depositing a self-assembled monolayer on its surface. This combined approach of engineering both the bulk and surface properties of ZnO results in significant improvements in the performance of planar MAPbI3 perovskite solar cells with a maximum power conversion efficiency of 18%, accompanied by a reduction in hysteresis and a significant enhancement of the device stability. Our work makes engineered solution-processed ZnO layers a practical alternative to TiO2 as electron extraction layers in perovskite solar cells, while also eliminating the need for high temperature sintering steps from the device fabrication.

Fast Pulse Combustion Process for Producing Lithium-Ion Cathode Materials

With the use of a fast pulse combustion process in a reactor we are able to produce LiFePO4, albeit with the use of an additional annealing step[1]. The role of latter is to introduce appropriate ordering into the structure. Disorder in the crystal structure of LiFePO4 has been identified by many groups[2–4], especially for materials synthesized via reactions without a high-temperature sintering step in an inert or reducing atmosphere, or using fast reactions on the order of minutes[5,6]. The most favorable intrinsic defect is the Li-Fe ‘anti-site’ pair in which the Li ion (on the M1 site) and the Fe ion (on the M2 site) are interchanged[2]. In this report we show that such a disordered structure can be obtained even with synthesis times shorter than 2 seconds; at such short times one usually obtains amorphous materials[7]. The disorder will be observed through Mossbauer analysis and Rietveld refinement of XRD data. The galvanostatic cycling behavior of such disordered LiFePO4 is shown together with the annealed version on the attached graph. We were able to cycle the former up to a current density of 340 mA/g (corresponds to 2C). Another group of interesting cathode materials is the lithium nickel manganese cobalt oxides. Using different ratios between the three transition metals different compositions can be obtained, some showing a very high capacity of 220 mAh/g when charged to 4.7 V[8,9]. With our method we are able to produce a wide range of compositions, also lithium rich ones. This is possible because of the very fast reaction from solutions of metal salts, where the mixing proceeds on the molecular level. The fast reaction is the reason that no phase separation or grouping of an element can occur, leading to a uniform composition across the whole material. Simultaneously the method also allows decoration of the particles with a carbon coating, which could help improve the capacity retention[9]. The synthesis of present cathode materials was carried out in a pulse combustion reactor[1], which uses the pulsating flow of flue gases from the combustion chamber to supply the necessary energy for the reaction. The pulsating flow is a result of pulsating fuel and air ignition. It has been shown previously that this kind of burning has a better heat transfer rate than similar turbulent flows[10]. The flue gases enter the reactor pipe that has a two fluid nozzle at the point of flue gas entry. The nozzle is used to produce droplets of precursor in the hot zone of the reactor. The solvent from the droplets evaporates at a very high rate causing formation of agglomerated nano powders, which are then fully or partly crystallized after passing through the heated reactor pipe. The desired temperature in the reactor depends on the product. The dried precursor undergoes a reaction, similar to that in the solution combustion synthesis[11] (SCS), because the precursor can be composed of nitrates and a carbohydrate, acting as a fuel. Another possible precursor type are flammable precursors, such as those used in liquid feed flame spray pyrolysis[7,12](LF-FSP), however, they are usually not used in production of cathode materials with this reactor.

The Role of Aluminium in the Synthesis of Mesoporous 4H Silicon Carbide

Aluminium is found to play a key role in the process of forming a mechanically stable and highly porous and granular structure of 4H silicon carbide. The material is prepared by a high temperature reaction of the elemental constituents. The reactions are carried out under different background atmospheres, including nitrogen. Ternary carbides containing Al, Si and N, are formed in the process, and are believed to be responsible for the final outcome of the process, at the highest reaction temperatures, in the form of pure, well-connected grains of 4H-SiC forming a strong and rigid structure with high porosity. The Al containing compounds function as structural promoters for the 4H polytype recrystallization. This is expected - and partly shown - to take place through substitution with 4H-SiC and evaporation of all other constituents during the high temperature sintering step. When extruded into honeycomb structures prior to the sintering process this pure mesoporous SiC final product turns out to be ideal for a combined diesel particulate filter with support for catalysts in the pores.

Comment on “High-temperature soft magnetic properties of antiperovskite nitrides ZnNFe3 and AlNFe3” by Yankun Fu, Shuai Lin, and Bosen Wang, J. Magn. Magn. Mater. 378 (2015) 54–58

The authors of the aforementioned manuscript have recently claimed the synthesis of the ternary nitrides ZnNFe3 (=ZnFe3N) and AlNFe3 (=AlFe3N), ordered substituted variants of the binary phase γ‘-Fe4N [1]. While soft ferromagnets of such kind are presently attracting lots of attention, their history dates back for more than half a century. In particular, Al-substituted γ‘-Fe4N has already been mentioned in 1961 [2], and the existence of AlFe3N has also been claimed in 2009 [3] from a two-step ammonolysis reaction combining a high-temperature sintering step and a low-temperature nitriding reaction [4]. Nonetheless, one of us had to withdraw the latter claim after finding out, by means of scanning-electron microscopy and elemental mapping, that all samples of “AlFe3N” consisted of an intimate solid mixture of γ‘-Fe4N and amorphous Al2O3[5]. From what follows, we have strong reasons to believe that the authors of Ref. [1] overlooked our findings [5] and also did not synthesize ZnFe3N and AlFe3N.

Solid-state reactive sintering mechanism for proton conducting ceramics

Abstract The recently developed solid-state reactive sintering (SSRS) method significantly simplifies the fabrication process for proton conducting ceramics by combining phase formation, densification, and grain growth into a single high-temperature sintering step. The fabrication simplicity provided by SSRS greatly enhances the potential for deployment of proton conducting ceramics in a number of electrochemical devices. Nevertheless, the mechanisms behind SSRS are still poorly understood. In this report, the SSRS mechanism is clarified through a systematic study of the effect of a suite of metal oxide sintering additives on the phase formation and densification of prototypical proton conducting ceramics BaCe 0.6 Zr 0.3 Y 0.1 O 3 − δ (BCZY63), BaCe 0.8 Y 0.2 O 3 − δ (BCY20), BaZr 0.8 Y 0.2 O 3 − δ (BZY20), and BaZr 0.9 Y 0.1 O 3 − δ (BZY10). Sintering additives with metal ions having a stable oxidation state of + 2 and an ionic radius similar to Zr 4 + (which easily occupy the Zr 4 + site of the BaZrO 3 perovskite structure, resulting in the formation of large amounts of defects) produce the best sinterability. Sintering additives with metal ions having multiple stable oxidation states (2 +, 3 +, 4 + etc.) and ionic radii near to Zr 4 + (which also readily occupy the Zr 4 + sites of BaZrO 3 perovskite structure, but form fewer amounts of defects) can result in partial sintering by the formation of mechanically stable highly-porous microstructures with limited grain sizes. Sintering additives with metal ions having stable oxidation states ≥ 3 + or ionic radii far from Zr 4 + are unlikely to form a solid solution with BaZrO 3 and yield no effect on sintering behavior (virtually identical to the control sample without any additives). These findings provide a useful guide for the selection of sintering additives to engineer optimal microstructures in proton conducting ceramics and may have potential consequences in other ceramic systems as well.

Preparation, material analysis, and morphology of Cr2 − xTixO3 + z for gas sensors

AbstractTitanium substituted chromium oxide (Cr2 − xTixO3 + z, CTO) has gained increasing interest concerning gas sensing applications. CTO is prepared by synthesis of chromium oxide and titanium oxide. Different techniques for verification of successful synthesis of CTO have been investigated. Solid state Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy were performed in addition to the common analysis via X‐ray diffraction (XRD). The spectroscopic methods offer a fast, qualitative verification of a complete synthesis. CTO was synthesized in a high temperature sintering step, and powders and dispersions of CTO were prepared. A high energy grinding process leads to the required particle size reduction. The size distribution and crystallite size of the CTO particles were measured. Furthermore morphology and surface coverage analysis on novel type gas‐sensing CTO layers, deposited via inkjet technology, were performed and specific adsorption energies of nitrogen dioxide on printed CTO layers were derived. High porosity with sub‐micron particles was shown to be characteristic for the layers, resulting in a highly sensitive gas‐sensing behavior, with 500 ppb of nitrogen dioxide being clearly detectable.

Application of CIP processing and sol-gel surface coating to PZN-PZT piezoelectric ceramics for use as energy harvesters

Piezoelectric 0.2Pb(Zn 1/3Nb 2/3)O 3-0.8Pb(Zr 1/2Ti 1/2)O 3 (PZN-PZT) ceramics in disc form were fabricated and characterized for use as energy harvester devices. A powder mixture with an average particle size of about 1 μm with the addition of 0.5 wt% ZnO was used to obtain a high piezoelectric coefficient and low sintering temperature. A molding method, including cold isostatic pressing (CIP), was used to resolve the cracking and bending problems of thin ceramics during the high-temperature post-processing sintering step. A sol-gel surface coating was found to be very effective for ceramic discs with a very high piezoelectric constant d 33 of 536 pC/N. The results of this study could be applicable to small piezoelectric energy harvester devices.

Room-temperature preparation of crystalline TiO 2 thin films and their applications in polymer/TiO 2 hybrid optoelectronic devices

Highly homogeneous crystalline TiO 2 thin films with very low surface roughness were prepared by spin-coating of a TiO 2 nanoparticle aqueous dispersion at room temperature without further heat treatment. Using these films as electron transporting layers, inverted structure hybrid photovoltaic cells (TiO 2/P3HT) and light-emitting diodes (TiO 2/F8BT) were demonstrated. The photovoltaic cells exhibited an energy conversion efficiency of 0.26%, which is similar to that of cells utilizing TiO 2 layers sintered at high temperatures. Moreover, the light-emitting diodes showed an efficiency of 0.65 cd/A, which is higher than obtained from a reference inverted diode (0.1 cd/A). These measurements demonstrate that a properly designed nanoparticle casting route can help avoid high temperature crystallization or sintering steps for TiO 2 thin films, paving the road for their use in conjunction with plastic substrates.

Two-stage Laser Thermal Processing of Nanoparticle Inks on Flexible Substrates for High Performance Electronics

ABSTRACTZinc oxide is a promising semiconductor film for active devices on flexible substrates, and synthesis routes using nanoparticle inks enable greater variety of applications. We introduce and characterize a two-step transient laser annealing process to create fully densified zinc oxide films from nanoparticle ink precursors. A low temperature sub-millisecond calcining step to remove solvent and organic stabilizing ligands was followed by a high-temperature pulsed laser sintering step to form densified 50-100 nm thin films with resistivities of 10-1 to 10-3 Ω-cm. Film microstructures can be varied between crystalline and amorphous without significant film damage by adjusting the fluence of the high-temperature sintering step. These processes would be compatible with a variety of nanoparticle species, deposition methods, and patterning methods, including roll-to-roll processing paradigms.

Cost-effective solid-state reactive sintering method for high conductivity proton conducting yttrium-doped barium zirconium ceramics

Using cost-effective precursors of BaCO 3, ZrO 2, and Y 2O 3, proton conducting ceramic pellets of BaZr 0.8Y 0.2O 3 − δ (BZY20) were successfully fabricated with the help of a range of sintering aids including LiF, NiO, Al 2O 3, and SnO 2. This simple and cost-effective solid-state reactive sintering (SSRS) method involved only a single high-temperature sintering step. The effect of various experimental conditions on the crystal structure, relative density, morphology, and total conductivity of the as-prepared BZY20 ceramic pellets were investigated in detail. Tunable experimental parameters included the type of sintering aid, the amount of aid, and the sintering temperature. NiO was determined to be the most effective sintering aid investigated. Under optimized conditions using 1–2 wt.% NiO as a sintering aid, dense BZY20 ceramic pellets (> 95% relative density) with grain sizes as large as 5 μm were successfully prepared at a relatively low sintering temperature of 1400 °C. In comparison, most alternative sintering techniques for BZY require temperatures in excess of 1700 °C. Total conductivities as high as 2.2 × 10 − 2 and 3.3 × 10 − 2 S cm − 1 were obtained from the resulting pellets at 600 °C under dry- and wet-argon atmospheres respectively. These are among the highest values reported for BZY20, highlighting the potential of the NiO-modified reactive sintering approach to provide a simple, cost-effective, reduced-temperature route to achieve dense, large-grained parts for protonic-ceramic applications.